1. Field of the Invention
The present invention relates to a coloring composition. Specifically, it relates to a coloring composition which is suitable for forming colored pixels. The present invention also relates to a cured film, a color filter, a solid-state imaging device, and an image display device, each using the coloring composition. The present invention also relates to a pattern forming method and a method for manufacturing a color filter, using the coloring composition. In addition, the present invention also relates to a dye multimer for use in the coloring composition.
2. Description of the Related Art
Recently, there is a significantly growing demand for solid-state imaging devices such as CCD image sensors along with the widespread use of digital cameras, cell phones equipped with cameras, and the like. Color filters are used as key devices of displays or optical elements of these devices, and are increasingly required to be more sensitive and smaller. Such color filters typically have a colored pattern of three primary colors, i.e., red (R), green (G), and blue (B), and have a role in decomposing the light transmitted through it into the three primary colors.
Coloring agents for use in color filters are commonly required to satisfy the following requirements. That is, the colorants are required to have preferable spectral characteristics in terms of color reproducibility; not to exhibit optical disorders as unevenness in optical densities that may cause light scattering or color unevenness/roughness; to have good fastness against environmental conditions under which the devices are manufactured and used, such as heat resistance and light fastness; to have a large molar light absorption coefficient and enable formation of a thin film; and the like.
As one of methods for manufacturing the color filter, there is a pigment dispersion method. The pigment dispersion method for manufacturing the color filter by a photolithography method or an ink jet printing method is stable against light and heat due to use of pigments. However, it problems such as light scattering and color unevenness/roughness often occurs since the pigments themselves are microparticles. Micronization of pigments is carried out so as to overcome these problems, but there is a problem in that it is not compatible with dispersion stability.
An alternative method to the pigment dispersion method for manufacturing the color filter may be a method using a dye as a color material. The dye is dissolved in a resist so that it can suppress light scattering or color unevenness/roughness as with a pigment. The dye has problems in that it is deteriorated in heat resistance or light fastness, as compared with the pigment. For solving the problems, dyes with excellent rigidity have recently been developed (see, for example, JP2008-292970A and JP2010-18788A).
Furthermore, in a coloring composition including a dye, in the case of carrying out a heating treatment after forming a film, it is pointed out that a phenomenon that color transfer among colored adjacent patterns having different colors and overlapping laminated layers easily occurs. With regard to this problem, a method in which a colorant is polymerized so as to solve the problem is disclosed (see, for example, JP2007-139906A, JP2007-138051A, JP2000-162429A, JP2011-95732A, JP2013-029760A, and JP2012-32754A).
In addition, many color materials having excellent light fastness have recently been developed, but it is known that a photostabilizer is separately added to a coloring composition in order to further impart light fastness (see, for example, JP2010-54808A (JP5141448B)).
Non-Patent Document 1: Dyes and Pigments 74 (207) 187-194 is an example of the related art.